The present specification relates to displays. More particularly, the present specification relates to head-mounted and helmet-mounted displays (HMDs), a collimated virtual window, or head up display (HUD). Head mounted displays are also referred to as head worn displays (HWDs or simply HDs).
HUDs and HMDs provide significant safety and operational benefits. In avionic applications, HUDs and HMDs can provide the pilot with flight information and enhanced situational awareness in degraded visual environments. These operational and safety benefits can be important to operators of air transport aircraft, regional aircraft, high end business jets, smaller private aircraft, and military aircraft. In the case of military aircraft, HUDs and HMDs can also provide pilots with mission-critical information and targeting cues.
Substrate guided displays which use waveguide technology with diffraction gratings to preserve eye box size while reducing size of the projection optics have been proposed. U.S. Pat. No. 4,309,070 issued St. Leger Searle and U.S. Pat. No. 4,711,512 issued to Upatnieks disclose substrate waveguide head-up displays (HUDs). U.S. Pat. Nos. 8,749,890, 8,634,139, and 8,659,826, all incorporated herein by reference and assigned to the assignee of the present application, also disclose waveguide displays (including but not limited to HUDs and HMDs for use in cockpit and other environments.
There is a need for a HMD or HUD with a curved combiner. Further, there is a need for a HMD or HUD which uses a curved substrate waveguide combiner. There is a need for a HMD or HUD with a curved combiner which is lightweight and esthetically attractive. Yet further, there is a need for a collimating projector for a curved substrate waveguide HMD or HUD with acceptable wavefront errors. Still further, there is a need for curved waveguide combiner for a helmet, goggles or glasses that creates a collimated image with acceptable wavefront errors. Still further, there is a need for curved waveguide combiner for a collimated virtual window.